Esfalerita
Esfalerita is a mineral with formula ZnS, in the Sulfuros group. This specimen comes from Mina Troya, Mutiloa, Gipuzkoa, Euskadi, España and joined the Terrium collection in 2019.
Description
Crystals with good lustre and dark caramel tones, with visible growth features.
History of this specimen
A "resurrected" piece. It turned up in 2025 while I was organising the almacén with Óscar, opening boxes still unopened from several moves before the house in Cariño. He bought it at the Mercadillo de la Escuela de Minas in 2019, and it has lain dormant for 6 years awaiting its official cataloguing.
About Esfalerita
It is the principal zinc mineral. A sulphide that can crystallise as octahedra and dodecahedra. The gemmological quality of the "caramel" varieties from this locality is highly valued.
About the locality
A historic European reference locality. Worked by Exminesa between 1986 and 1993, when a collapse forced its closure. It was an underground lead-zinc gallery over one kilometre long. Its large geodes (even several cubic metres) produced some of the best sphalerites from Spain, much sought after for their transparency and honey-cognac colour. Closed and flooded since 2009, today only its tailings pond remains.
Technical data
- Catalogue No.
- 0315
- Composition
- ZnS
- Name
- Esfalerita
- Group
- Sulfuros
- Category
- Cupidium
- Matrix
- galena
- Associations
- calcita
- Mine
- Mina Troya
- District / Municipality
- Mutiloa
- Province
- Gipuzkoa
- Region
- Euskadi
- Country
- España
- Size (cm)
- 4.8 x 4 x 2.8
- Weight
- 47.8 g
- Acquired
- 2019
- Etymology
- The name of this mineral is a fossilised miners' insult. Early German miners called it "Blende" (from the verb blenden, 'to deceive') because its lustre promised good metals (lead or silver), but when smelted to extract value… nothing good came out. Scientific nomenclature kept the affront: in 1847 it was named sphalerite, from the Greek "sphaleros", literally 'treacherous!'. It is the spiritual sister of pitchblende; another slight in its name and two 'lying' minerals that frustrated generations of miners.
- Quality
- Muy buena
- Value trend
- Al alza
Related specimens
- Abellaíta — España
- Abernathyita — España
- Abernathyita — España
- Abernathyita — España
- Acantita (Paramórfica tras Argentita) — Marruecos
- Aerenita — España
- Aerinita (fibrosa) — España
- Analcima — España